Gemstone Education

Gemstone jewelry makes for a beautiful gift for yourself or the special people in your life. We at Vinciguerra Jewelers are here to provide you with everything you need to know about gemstones. Whether it’s an engagement ring or fashion jewelry, we can help you find the perfect piece!

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The Four Cs of Gemstones

If you are in the market to buy a piece of jewelry that features a gemstone, you must be aware of the features of the gemstones, which help to place value on the piece during an appraisal. The valuation of a gemstone comes from the four Cs: carat, color, clarity, and cut.

  • Carat Weight: The weight of a gemstone is given as its carat weight. Carat is equivalent to one-fifth of a gram, and carat weights are expected to be given to the one-hundredth carat (2.45 carats, for example). In the past, it was common to see the weight given as a fraction (⅝ carat, for example), but this is no longer precise enough since gemstones are priced by the carat.
  • Color: Regarding gemstones, color is generally the most important value aspect. Each gemstone has a particular color or range of colors, and the more variation a gemstone has from that color (lighter, darker, more or less vivid), the more it loses its value. Color has three distinct dimensions, making it far more complicated than simply deciding it is a certain color. These dimensions are hue (impression of color), tone (degree of lightness or darkness), and saturation (degree of purity to the hue).
  • Clarity: Inclusions on the inside of the gem or blemishes on the outside determine a gem’s clarity. If someone refers to the cloudiness of a gem, they are likely referring to the inclusions which have formed inside the gem. These can include bubbles, small pockets of liquid, minute crystals of the same or different mineral, and fractures or cleavages. Inclusions can have a serious impact on the value of a diamond, but inclusions are not necessarily always a negative feature since those which create stars or a flash can enhance the gem’s beauty. Blemishes are features outside of a gem such as chips, scratches, abrasions, naturals on diamonds, and spots on pearls.
  • Cut: Cut of the gemstone has a few properties: shape or design of the stone, arrangement of facets, precision of stone’s proportions, and finish.

What’s the Difference Between Precious and Semi-Precious Stones?

In the mid-1800s, gemstones were divided into two categories: precious and semi-precious. These terms became very popular and used ubiquitously throughout the gemstone and jewelry industry. While they are still commonly used today, the terms can be misleading because it can make people believe that the precious stones are more valuable or desirable than semi-precious ones when that is not the case.

  • Precious is a term that refers to gems of four types: diamonds, rubies, sapphires, and emeralds. These stones are usually transparent, cut by facing, and generally cost more per carat than semi-precious stones, especially in the United States.
  • Semi-precious stones encompass a wide variety of gems fashioned from materials including agate, amethyst, aquamarine, jade, hematite, garnet, obsidian, onyx, turquoise, peridot, and many others. Some semi-precious stones have been sold for far higher prices per carat than many precious stones, and many semi-precious stones are more rare than precious stones.

While the terms “precious” and “semi-precious” have been widely used for many years, they should not be applied to the quality or grade of a gemstone. Some in the industry have even suggested dropping the terms completely because of their misleading connotations.

Most Common Gemstones for Jewelry

No matter what your style, taste, or aesthetic, there is a gemstone (precious or semi-precious) to suit your desires. In the jewelry industry, there are so many gemstones that can be used to make the perfect piece, and the list below describes the most common and most popular.

Precious Stones


Almost everyone is familiar with or has seen a diamond, the hardest of all gems. It is made up of only one element – carbon. They form deep within the earth and are over a billion years old! They are prized for their colorless nature and purity, and many brides-to-be have engagement rings that feature a gorgeous diamond. No matter what your style or aesthetic, a diamond is the perfect way to ensure you get the high-end look you want. At Vinciguerra Jewelers, our diamond experts will work with you to make sure your diamond jewelry is exactly what you desire.


Ruby is the most valuable variety of the corundum mineral species. The red color comes from trace amounts of chromium in the stone. It is a hard gemstone, but the color enhancement techniques often used in rubies may fade the stone over time. It is best to avoid harsh treatment, strong chemicals, abrasives, and direct heat to ensure your ruby does not fade.


Any corundum that is not a ruby can be considered a sapphire. Their color can vary depending on the trace element content, so a sapphire can be blue, yellow, green, orange, pink, purple, or a six-rayed star when cut as a cabochon. Sapphires are unusually durable, so normal cleaning care can be utilized. Direct heat should still be avoided.


If Spanish conquistadors, Inca kings, Moguls, and pharaohs all felt the emerald was a gem to be prized, you simply can’t go wrong with this bluish green to green variety of the mineral species beryl. Cleaning an emerald is more delicate than some other gemstones because they are oiled and usually have inclusions, so ultrasonic cleaners should be avoided. A small brush with lukewarm water will suffice. As with many other stones, avoid sudden temperature changes and sharp blows.

Semi-Precious Stones


Agate is a translucent variety of microcrystalline quartz that forms by deposits of silica from groundwater in the cavities of igneous rocks. Because the deposits form in layers, the agate itself has a banded pattern which makes them truly unique and desirable for jewelry. They come in a wide range of colors including brown, white, red, gray, pink, black, and yellow, and these colors are actually caused by impurities that alternate in bands throughout the stone.


Amber is an organic gem, which is the product of living or once-living organisms. Amber is considered to be nature’s time capsule, as 1,000 extinct animal species and various types of plant matter have been identified in amber. This fossilized tree resin is usually sun-orange or golden brown. The color may darken over time if exposed to an overabundance of light.


Amethyst is an extremely versatile, purple variety of the mineral quartz and often forms large, six-sided crystals. It has been used in many different jewelry types from class rings for high school seniors all the way up to the royal crown jewels. Amethyst is very durable and is fine to clean through normal processes. Overexposure to light or heat can fade or weaken its color.


Looking at the aquamarine gemstone is like peering deep into the ocean for miles, and that is where it derives its name. This variety of the mineral beryl is slightly greenish-blue and can sometimes grow big enough to fashion gems of over 100 carats! For cleaning, do not use an ultrasonic machine, and to retain its beautiful color be sure to stay away from heat.


As a variety of quartz, citrine is transparent and tends to be pale yellow to brownish orange because of the trace amounts of iron found in it. It is commonly substituted for topaz and yellow sapphire. Normal cleaning processes are fine but do not expose it to excessive light or heat in order to retain its color.


While many are familiar with the fiery red version of garnet, these closely related minerals form a group with gemstones in many different colors including orange and green. They can also exhibit amazing characteristics such as a star effect or a color changing effect under certain lighting conditions. Garnet is the January birthstone and can be faceted as cabochons or beads. They are very durable and can handle normal cleaning processes.


This gem is quite unique in that jade is actually two separate gems, nephrite and jadeite. They are commonly used in stunning artistic pieces and have been prized by civilizations for centuries, especially in China and for the Aztecs and Mayans of Central America.


In the gemstone world, Kunzite is pretty new. It was only established as a unique variety of spodumene in the early twentieth century, but it has become a collector favorite due to its range of color from pastel pink to violet purple.


When you look at a moonstone, you may get lost in its billowy blue adularescence. The glow just beneath the surface of this feldspar is caused by light scattering from the intergrowth of microscopic, alternating layers. It is a haunting gem often used in the designs of Art Nouveau jewelers.


Opals are unique and fascinating because of the spectrum of colors called the “play-of-color” that can be seen in different types of lighting. In addition to the play-of-color, they can be colorless, opaque, translucent, or transparent. Because they only have a hardness of 5.0-6.5, they are rarely faceted but can be cut as cabochons or used as beads. They are also the October birthstone.


Chalcedony, known as onyx, is the most traditional black gemstone, although it can also be banded black and white. Onyx has been used in jewelry and ornamental designs since antiquity, and it is mostly cut into cabochons and beads in our modern time. Though more popular in previous centuries, onyx still remains highly prized, especially for cameos, intaglios, carvings, statues, and jewelry pieces including bracelets, necklaces, earrings, and rings.


A string of pearls used to be a jewelry staple for most women and for good reason. Pearls are shining spheres produced by marine and freshwater mollusks naturally or cultured by people. They are smooth and subtle which makes them ideal for the perfect accent piece for any equally perfect outfit. After wearing your pearls, you should clean them with a soft cloth. Occasionally, you can use mild non-detergent soap or commercial jewelry cleaner made for pearls. They are soft and easy to scratch, so great caution must be taken when handling or cleaning pearls. To avoid cracking or discoloration, keep them out of the heat, and store them in a dry area since pearls will draw moisture.


For those with the August birthday, the gem found in lava, meteorites, and deep in the earth’s mantle is for you. This yellow-green gem is the peridot and is a variety of the mineral olivine. To clean your peridot jewelry, avoid ultrasonic machines.


Found only in Tanzania near Mount Kilimanjaro in 1967, Tanzanite is a purplish blue to pure blue variety of the mineral species zoisite. It has quickly become one of the most popular of the colored gemstones, especially for those born in December. Tanzanite has a hardness of 6.0-7.0 on the Mohs Hardness Scale, but it is still delicate and should be handled with care and cleaned with a tightly woven microfiber cloth with warm, soapy water.


For those with November birthdays, Topaz is your go-to gemstone. It is warm and beautiful and comes in a variety of colors including pink, orange, red, purple, brown, yellow, or even colorless. It is quite durable (8.0 on the Mohs Hardness Scale), can be cut into a variety of shapes and sizes, and is found primarily in Brazil. Bright light for extended periods may fade the stone, and ultrasonic cleaners can harm the stone as well. Use a tightly woven microfiber cloth with warm, soapy water for best cleaning.


One visit to the southwest states like New Mexico and Arizona will get you enamored with the opaque mineral turquoise. It is found in shades of blue, bluish green, green, and yellowish green and is a rare phosphate of copper that forms in the earth’s driest and most barren regions.

The list of semi-precious gemstones can go on and on but those above are the most common gemstones used to create gorgeous pieces of jewelry.


In the first century, the concept of a gemstone’s connection to a specific month of the year developed. The belief was that there was a connection between the twelve stones of the priestly breastplate, the twelve months of the year, and the twelve signs of the zodiac. The standardization of one stone for each month occurred in 1912 and was completed by the Jewelers of America.

It is quite common for people to feel a therapeutic influence or healing power when wearing the gemstone associated with that month. There are many legends and myths about the healing properties of birthstones and how wearing the one assigned to a specific month can heighten the supposed power of the stone itself.

At Vinciguerra Jewelers, we believe that wearing jewelry that features your birthstone is a fantastic way to represent yourself and your uniqueness. Our jewelers can help you find the perfect personalized jewelry with the appropriate gemstone for your birth month.

The birth month gemstones are as follows:

  • January: Garnet
  • February: Amethyst
  • March: Aquamarine, Bloodstone
  • April: Diamond
  • May: Emerald
  • June: Pearl, Moonstone, Alexandrite
  • July: Ruby
  • August: Peridot, Spinel
  • September: Sapphire
  • October: Opal, Tourmaline
  • November: Topaz, Citrine
  • December: Turquoise, Zircon, Tanzanite

Contact us today to learn more about our personalization services and how our jewelers can work to find you the perfect piece with a birth month gemstone!

Caring for Gemstones

When you have made the investment in a beautiful piece of jewelry that features a gemstone, it is important that you take the proper steps to maintain its brilliance and beauty. In general, jewelry should be stored in a clean, dry place, preferably in a fabric-lined case. Keep jewelry pieces away from each other since they can get tangled and scratched. You should bring your jewelry to our expert jewelers at Vinciguerra Jewelers at least once per year for regular maintenance and professional cleaning. We can also repair your pieces and bring them back to their original functionality and brilliance.

If you have diamond jewelry such as an engagement or wedding ring, it is important that you not take its durability for granted. Although diamond is one of the toughest materials on earth, it can still be scratched or chipped by a sudden, sharp blow. Avoid wearing diamond jewelry when doing rough work or using harsh chemicals such as chlorine. Clean your diamonds regularly with a commercial cleaner, a mix of water and ammonia, or mild detergent. You can dislodge dust and dirt from under the setting with a soft brush. Try to avoid touching the diamond as well since your fingers can smudge it.

For various colored gemstones, there are many which require very specific care and service to maintain their beauty. At Vinciguerra Jewelers, we are happy to discuss the proper way to care for your jewelry, but we will provide you a few general care tips here. After each instance of wearing your gemstone jewelry, wipe it thoroughly with a clean, soft, slightly damp cloth to maintain its brilliance and ensure it is clean for storage. Store your gemstones individually in soft pouches. Avoid harsh chemicals when wearing your gemstones and apply any makeup or other cosmetics prior to putting on your gemstones to avoid dulling the stones.

St. Louis, MO Jewelry Store

As a family-owned jewelry store operating since 1951, Vinciguerra Jewelers is committed to providing friendly customer service and high-quality jewelry services. We are the premier jewelers in St. Louis, Missouri, and we want to help you make a special occasion even more spectacular with one of our exquisite jewelry pieces. We have a variety of styles for you to choose from, and we are sure that we can get you the jewelry piece you have been waiting for. Let us help you find the perfect piece of gemstone jewelry today!

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